The Anniversary Speed Graphic will either have a "spring" back (which takes conventional sheet-film holders) or a "Graflex" back like the back on a Graflex SLR. The latter is fairly rare.
Jo Lommens website has clear illustrations of the different backs found on Graphic and Graflex cameras:
http://lommen9.home.xs4all.nl/holders/index.html
If your camera has the common spring back, only a slip-in Adapt-A-Roll 620 holder will fit:
http://graflex.org/speed-graphic/adapt-a-roll.html
The alternative is a DIY project explained here:
http://www.graflex.org/speed-graphic/graphic-back-conversion.html
The "spring kit" mentioned in the article above sometimes shows up on the auction site. I managed to find one there after persistent looking.
It took me quite a while to figure out the mystery of Graflex-Graphic backs!
Good luck.

You have to be very careful. For instance, the following current listing on the auction site is the right size but it is made for a Graflex back (i.e. for a Graflex SLR or the rare Graphic equipped with a Graflex back):
http://www.ebay.ca/itm/23-GRAFLEX-120-roll-holder-film-back-3-1-4-X-4-1-4-/200637108882?pt=US_Film_Backs_Holders&hash=item2eb6e75292
The Graflex company did not make a roll-film holder for the older spring-back Graphics like the Anniversary series (1940-1946). The roll-film holders labelled "Graphic" will only fit the Crown and Speed Graphics equipped with a Graflok back, which was not introduced until 1951 or so. Here is a listing for one of these, which will fit only on a Graflok back -- not a spring back:
http://www.ebay.ca/itm/Graflex-Graphic-22-Roll-Film-Back-120-Film-BACK-/360356596406?pt=Film_Cameras&hash=item53e6ed4ab6
I speak from experience. For a spring back the ideal solution is an Adapt-A-Roll 620 in the 3x4 size. This will slip right in when you pull the ground-glass back against the springs.
The other alternative is a DIY improvised spring kit like the one on this site that I referred you to in my previous post. A more technically adept Graflex.org member than I may be able to advise you on how to cobble together one of these in the 3x4 size.
If you can find an official Graphic spring kit in the right size, you wouldn't have to improvise, but these are rare and sellers usually charge a hefty price for them.

Thanks again. I think I can probably make something that will hold it as well. I'm getting back into photography after a 30+ year hiatus & discoveering I for got a bunch. I got a Crown at an estate sale & was offered the 3 1/4x4 1/4 by a friend who had never used it. I figured I'd pick up a 120 back & use it as my point & shoot(!) since my Bronica is too @#$!% heavy. I'll buy that #23 & if I can figure a way to mount it, I'll post it. Thanks for your help & ideas!

Look at the right side of the holder in auction picture 3 from left of the first linked RFH. The grove forms the light trap on GRAFLEX type backs.
Look at the right side of the 9th picture from top in the description of the second linked RFH, the camera side has two ribs a short distance apart. This is the light trap for GRAPHIC and GRAFLOK backs. This RFH can be fitted to a GRAPHIC back with a spring kit or self fabricated retainer. The seller does not list what format the RFH is for. It appears to be for 4x5.

A device that film is put into so it can be exposed in a camera is called a FILM HOLDER. The framework on the rear of a camera that holds film holders in place is called the CAMERA BACK.

Graflex Corp. (aka the company) used many variations of Graph labeling their products. Most will have Graflex in the name making things more confusing to someone not familiar with the products._________________The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.